Overall objectives: The Core Laboratory in Analytical Chemistry is the chemical analysis arm of the Center for Environmental Health Sciences. It is a central resource in analytical chemistry for Program Project participants, providing them with analytical expertise, training, and access to analytical instrumentation. A major CEHS goal is to foster collaborative research among combustion engineers, genetic toxicologists, analytical chemist, civil engineers and other investigators in order to solve important problems in human health effects research. The Core Lab in Analytical Chemistry is an important resource in making this research collaboration come to fruition. Specific aims: The Core Lab in Analytical Chemistry, operating in conjunction with the Core Lab in Toxicology, will work closely with the Project 1 research team (Sarofim, Howard, Cass) and Project 2 research team (Thilly, Crespi, Willey) to determine the most important human cell mutagens (MIMs) in ambient air samples from Los Angeles, CA; Woburn, MA; and Rochester, NY. In order to accomplish this objective, protocols based on bioassay-directed chemical analysis will be used. Relevant analytical methods and separation procedures will be developed and tested. When MIMs are identified, additional effort to determine their combustion sources and formation mechanisms will be initiated in collaboration with Project 1 Investigators. Relevance to human health: It is CEHS and Core Lab policy to focus major efforts on samples whose presence in the biosphere is likely to pose a threat to human health. To date, much of our work has focused on the characterization of polycyclic aromatic hydrocarbons (PAH) and derivatives emitted into the environment by combustion systems and on chemical emanating from Superfund sites in a nearby watershed. In the present Program, we will focus on the characterization of airborne chemicals because of (a) the observed urban excess of lung cancer, (b) clear human cell mutagenicity of airborne chemicals, (c) finding of PAH adducts in human lungs at mutagenic levels, and (d) the appearance of oncomutations in lung cancers of the kind associated with PAH.